Thursday, February 9, 2012

Instant Mold- How To Use It

I've recently run across a lot of posts on the internet which cover the use of Instant Mold or one of its variants. Often they miss a few things I've discovered (through trial and error) due to being a first or second time use and I was convinced that this would be a good time to do a thorough how to on the stuff that allows me to scratch build at an alarming rate (often too fast to paint!).

This is the stuff I'm talking about. If you are using another brand, results may vary as I have no experience outside this particular brand. I would assume (uh oh) that they would work in a fairly similar fashion and these tips and tricks will work for other brands of molding plastic.

1. When working with Instant Mold, be sure to use slightly hotter water than it states on the package. At 170 degrees Fahrenheit the mold cools too quickly and it may not have enough time to spread over the piece you wish to duplicate. I have found 208 to 215 degrees Fahrenheit works best.

2. With 1 part molds (molds that lay flat on one side) use something to put the piece in so the mold has a shape to conform to. What does this mean exactly? When making the mold often times small areas won't become properly filled in because pressure from multiple sides can't be applied. With an enclosure (ie sides) to force the mold material to stay within a confined area you will be able to apply more even pressure from the top. This will reduce imperfections.

3. Wipe off any excess water after removing the mold material. Imperfections are often caused by the water still sitting on the mold material that has no place to escape when forming around the cast piece.

4. Two part resin CAN be used with Instant Mold. The trick here is to only use it with smaller molds or apply multiple layers so the resin can't heat up to a temperature which will melt the plastic. It takes some experience to know how much is too much. The thinner the piece, the easier it is to cast in one go. Generally I've found that if there are less than 40 drops from each bottle (yes, I count the drops) you won't be melting the mold.

5. When using resin with two part molds, fill both sides to almost the top. Finish filling one side and allow them to cure. Now complete the part by filling the side which has the gap and put the two pieces together. Let the two sides cure together. Complete your piece by removing the two sides and trimming any excess.

If you use these simple tips and tricks, you'll have no problem making some fantastic duplicates. To show I'm actually talking from experience, here are some things I've used the Instant Mold to create.

8 comments:

{{4. Two part resin CAN be used with Instant Mold. The trick here is to only use it with smaller molds or apply multiple layers so the resin can't heat up to a temperature which will melt the plastic. It takes some experience to know how much is too much. The thinner the piece, the easier it is to cast in one go. Generally I've found that if there are less than 40 drops from each bottle (yes, I count the drops) you won't be melting the mold.}}

So if i have the idea right from the above statement, you basically are brushing the resin or something similar to brushing into the two sides, and then filling gaps later on. thus eliminating air pockets on the outside of the cast piece and also preventing melting of the instant mold. yes/ no/ maybe?? I'm asking because this would really help me finish my Warlock jetbikes the way i want to.

What I do is treat the two sides as one part molds until they are close to being filled and allow them to cure. Then I 'glue' the two halves together using resin on one side and placing the fully cured side half on top, being careful to have the two sides match up.

Because we are treating the pieces as 1 part molds, the air bubbles are apparent and visible to us and can be knocked loose with the back head of a stick pin before the resin begins to harden in most cases.

In fairly small amounts the resin won't heat enough to melt the plastic.

I wouldn't suggest brushing the resin on the mold unless you have a LOT of spare brushes lying around as it will definitely harden and become useless after the first attempt at this.

So, to clarify, I pour a little resin into both sides of the mold, carefully knock any air bubbles out of the recesses, allow them to cure, coat the top of one side with a little resin, and place the second half on top of the first, allowing it to cure. Remove your piece and trim any flash lines with a hobby knife. If you choose to use sand paper and sand away mold lines, wear a mask as the resin particles are toxic.

Hope I've helped clear things up and if you have more questions I'd be happy to answer them!

Nope, your statement is spot on to what I thought but a lot clearer than what I was trying to say myself. Thanks, as I said before this is really going to help me. Now I really do have an excuse to pick some of this stuff up from the game store.

What particular 2 part resin are you using in these? I can find a fair few around where I am, so I was curious what you use in your Insta-Mold casts. I've got a few hands/guns that I need to case soon, and I was originally going to use apoxy sculpt because I was afraid the exothermic reaction would distort the Insta-Mold. Resin would be a lot easier overall, and would save me a bunch of time.

I bought mine at Cool Mini or Not's store. A package of 6 sticks is around $13 and there is no limit to the number of times you use it. I bought two packages and I've made thousands of different parts with it. If the mold ever breaks, just get your original part again and recast it.